Powertrain
generic / SAE
P0641
Sensor Reference Voltage "A" Circuit Open
The 5 V reference voltage that the ECU supplies to multiple sensors (TPS, MAP, accelerator pedal, etc.) has dropped out or is open-circuit. Symptoms cascade — many sensor codes appear at once, all related to the same reference rail.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number6 / 41
Possible causes
- Reference wire shorted to ground (one defective sensor pulls the rail down) high
- ECM internal reference output failed medium
- Pin pushed back out of connector body low
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 80–1500 €
- Estimated time: 1–6 h
- Component: ecm
- Component: sensor reference wiring
- MIL / check engine light
- emissions-relevant
- limp mode possible
Sources
References
sae:J2012